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A217068 Least number m such that phi(m-6n) = phi(m) = phi(m+6n) and m is not divisible by n. 4
7991, 4096740829, 651, 25056, 23973, 41526, 1302, 5005333, 8175, 504, 1953, 2919396, 13737, 1054, 2257, 1708, 11521, 22313, 16350, 123098, 1008, 1584, 3906, 1887, 89027, 5335754, 27474, 59550082, 2108, 1344, 4514, 1512, 3416, 2925, 5859, 494379, 44626, 1586993, 8557 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,1

COMMENTS

a(n) has been computed by Donovan Johnson up to 200, but no values were found below 2*10^11 for n=41, 67, 113, 149, 157, 181.

LINKS

Table of n, a(n) for n=2..40.

F. Firoozbakht, Puzzle 466. phi(n-1)=phi(n)=phi(n+1), in C. Rivera's Primepuzzles.

S. W. Graham, J. J. Holt and C. Pomerance, On the solutions to phi(n) = phi(n+k) Number Theory in Progress, K. Gyory, H. Iwaniec, and J. Urbanowicz, eds., vol. 2, de Gruyter, Berlin and New York, 1999, pp. 867-882.

Donovan Johnson and Michel Marcus, a(n) for n=2 to 200, with missing terms shown as 0.

CROSSREFS

Cf. A000010, A217006.

Sequence in context: A233730 A175507 A126893 * A043614 A223285 A223482

Adjacent sequences:  A217065 A217066 A217067 * A217069 A217070 A217071

KEYWORD

nonn

AUTHOR

Michel Marcus, Sep 26 2012

STATUS

approved

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Last modified December 12 12:30 EST 2019. Contains 329958 sequences. (Running on oeis4.)